1. Field of the Disclosure
The disclosure relates to a bone cement and a method for producing same.
2. Description of the Related Art
Different types of bone cement are known from practice. In order to provide a biodegradable bone cement, i.e., a bone cement that is replaced over time after it is applied by new growth of bone tissue, bone cements based on calcium phosphate or calcium sulfate, for example, are known. After they are applied in each case, a sufficient initial stability can be achieved with these bone cements. Of course, the hardened material is very brittle, so that a sufficient permanent stability cannot be achieved for many cases of application. Calcium phosphates are also known. Of course, in the case of calcium phosphate-based bone cements, there is a softening of the material even after a short time, so that in many cases, defect sites cannot be stabilized sufficiently rapidly, particularly in elderly patients. Bone cements based on calcium sulfate or calcium phosphate-are generally not suitable for the anchoring of dynamic load-bearing implants.
For these applications, acrylic-based bone cements are generally used, and not only in elderly patients. These have the advantage of a high rigidity even after a brief hardening or curing. For the most part, a connective-tissue type of layer is formed around the implanted acrylic-based cement; bone material does not grow into the bone cement, but an acrylic-based bone cement is usually very well tolerated.
Acrylic-based bone cements generally cannot be degraded by the body. Therefore, attempts have been made to improve the biocompatibility of these types of cements, for example, by addition of hydroxyapatite. These types of additives for the most part, of course, are only accessible at the surface of the cement, predominantly surrounded by acrylic and for the most part are not resorbable. Finally, the known additive of calcium compounds can usually only improve the growth of tissue on the bone cement, but the quantity of accessible particles is usually not sufficient to achieve or to promote a new formation of bone in direct contact. Further, the opinion is offered that particularly in the case of vertebroplastic and kyphoplastic applications, the addition of calcium compounds is accompanied by disadvantages, since the E-modulus is increased based on the added particles, which can act negatively on the adjacent bone, in particular on the adjacent vertebral body. The danger of fracture that exists, without anything further, with the use of relatively solid acrylic-based bone cements thus may in fact be increased by the addition of hydroxyapatite particles.